1. Field of the Invention
This invention relates to a developing device in an image forming apparatus wherein a latent image such as an electrostatic latent image, a potential latent image or a magnetic latent image formed on the surface of an image bearing member such as a photosensitive member, a dielectric member or a magnetic member by electrophotography, electrostatic recording or magnetic recording is developed by a powder developer to thereby obtain an image, and in particular to a developing device adapted to be removably mounted with respect to the image forming apparatus.
2. Description of the Prior Art
As the construction of the developing device in an image forming apparatus, there is a housing for containing a developer therein and an opening is provided in the housing. A developer conveying member such as a developing sleeve for supplying the developer in the housing from the opening to the surface of an image bearing member is disposed so as to face the outside.
Now, in the case of maintenance, inspection or repair of the image forming apparatus body or the developing device, the developing device as described above is sometimes removed from the image forming apparatus body to smooth such work. Further, with the recent advance of the multicoloration of developer, it has become possible to obtain images of desired colors by interchanging developing devices exclusively for use with developers of various colors with respect to the image forming apparatus body and therefore, the occasion for removing the developing device from the image forming apparatus body has been increased. For this reason, the developing device has been improved so as to be readily removably mountable with respect to the image forming apparatus body.
However, when the developing device is removed from the image forming apparatus, the removed developing device is in a state in which the developer conveying member facing the outside through the opening of the housing is exposed. Therefore, the developer on the surface of the developer conveying member is liable to be scattered outwardly of the developing device by wind, vibration or an inadvertent touch with the exposed developer conveying member and thus, the floor or like place on which the removed developing device is placed, the operator's hands and clothes or the external surface of the developing device are liable to be stained by the developer. Also, the developer conveying member in its exposed state may inadvertently touch some other object and thereby the surface thereof may be damaged, or when the developer conveying member has some magnetism, magnetic materials such as small screws or metal pieces may be attracted by the magnetic force and if the operator re-mounts the developing device into the image forming apparatus without noticing it and operates the apparatus, the surface of said member may be injured to cause deterioration of formed images or otherwise hamper the normal function of the image forming apparatus body.
Also, in a developing device of the type in which there is provided a member which bears against the image bearing member and development is effected with a predetermined gap maintained thereby between the image bearing member and the developer conveying member, maintaining the gap constant is important to obtain good images. However, if the surface of the member which bears against the image bearing member is damaged, it will become difficult to maintain said gap always at a predetermined distance and accordingly, the gap between the image bearing member and the developer conveying member will fluctuate, and this will adversely affect the formed images.